Outcomes of astigmatic correction with and without two different cyclotorsion compensation methods in small incision lenticule extraction surgery

PURPOSE

To compare the astigmatic correction outcomes of small incision lenticule extraction (SMILE) surgery with or without two different cyclotorsion compensation methods.

METHODS

This is a prospective randomized clinical trial. Patients with myopic astigmatism that underwent SMILE surgery were randomly divided into static cyclotorsion compensated group (SCC group), slit-lamp group and control group. In the SCC and slit-lamp groups, the intraoperative cyclotorsion was manually compensated with different limbal marking methods. In the control group, the cyclotorsion was not compensated. Visual acuity and manifest refraction were measured preoperatively and postoperatively. Astigmatic outcomes were estimated with vector analysis.

RESULTS

A total of 94 eyes from 94 patients were analyzed postoperatively at the 3-month follow-up. Their mean preoperative cylinder was -1.56±0.86 D (range: -4.25 to -0.25 D). The mean preoperative spherical equivalent was -5.95±1.72 D (range: -10.50 to -2.75 D). All groups showed favorable results in the correction of myopic astigmatism. No statistically differences were found among three groups in postoperative visual acuity, refractive outcomes or vector parameters.

CONCLUSION

Cyclotorsion compensation with two different manual limbal marking methods was helpful in aligning the surgical position in SMILE, but it was not as effective as expected for the correction of myopic astigmatism under well controlled surgical positioning.

Relationship of Location Between Tear Film Center and Corneal Vertex Following Small-Incision Lenticule Extraction

Introduction

We aimed to measure the relationship of location between the tear film center (TFC) and corneal vertex (CV) following small incision lenticule extraction (SMILE).

Methods

A total of 100 consecutive patients (100 eyes) who underwent the SMILE procedure were included. Screen captures of intraoperative videos and pupillary offset were analyzed. Location was compared using a vector plot for the two reference points.

Results

The arithmetic values for the distance from the pupil center (PC) were almost identical between the TFC and CV (P = 0.118). The intraclass correlation coefficient (ICC) for the measures of distance from the CV and TFC to the PC was 0.659. The mean vector and standard deviation ellipse showed similar directional tendencies for both reference points. No significant difference was observed in the arithmetic values of decentration from the TFC and from the CV (P = 0.056). The ICC for the measures of decentration from the TFC and from the CV was 0.768. The difference in the distance from the PC was significant for the tear film mark (TFM) decentration group (P = 0.002, ICC = .480), while the difference in decentration was significant for the TFM centration group (P = 0 .000, ICC = 0.230).

Conclusions

The location of the CV in each eye could be simulated by the TFC. Furthermore, TFM decentered displacement could indicate optical zone decentered displacement.

Comparison of Toric Intraocular Lens Alignment Between Femtosecond Laser-Assisted Capsular Marking and Manual Corneal Marking

PURPOSE

To compare toric intraocular lens (IOL) alignment between femtosecond laser-assisted capsular marking and manual corneal marking.

METHODS

This study prospectively included 72 consecutive eyes (from 72 patients) with cataract and anterior corneal astigmatism of 1.00 diopter (D) or greater that underwent femtosecond laser-assisted cataract surgery with implantation of a toric IOL. These eyes were randomly categorized into two groups based on the IOL alignment method. The femtosecond laser capsular marking group included 36 eyes with capsular markers using the latest femtosecond laser platform. The manual marking group included 36 eyes with manual corneal markers. The preservation of the markers was assessed. Visual acuity and refractive outcomes, as well as deviation from the target axis, were evaluated.

RESULTS

In the femtosecond laser capsular marking group, all capsular markers were retained for at least 3 months. In the manual marking group, 22.2% of the corneal markers disappeared within 1 month and all markers disappeared within 3 months. At 1 month postoperatively, the mean magnitudes of refractive astigmatism were -0.41 ± 0.26 and -0.45 ± 0.31 D (P = .81), and the uncorrected distance visual acuities were 0.07 ± 0.06 and 0.07 ± 0.05 logMAR (P = .56) in the femtosecond laser capsular marking and manual marking groups, respectively. The misalignment of the toric IOL within 1 hour postoperatively was 1.5° ± 1.4° in the femtosecond laser capsular marking group and 4.4° ± 2.1° in the manual marking group (P < .01). The deviation from the target axis of implantation was 1.6° ± 1.3° in the femtosecond laser capsular group and 4.8° ± 2.5° in the manual marking group (P < .01) at 1 month postoperatively.

CONCLUSIONS

IOL misalignment was significantly lower in the femtosecond laser-assisted capsular marking group than in the manual corneal marking group. In addition, the long-term preservation of the capsular marker is helpful in evaluating the rotation of the toric IOL. [J Refract Surg. 2020;36(8):536-542.].

Comparison of the Distribution of Lenticule Decentration Following SMILE by Pupil Center or Tear Film Mark Centration

PURPOSE

To investigate lenticule decentration following small incision lenticule extraction (SMILE) via the pupil center or tear film mark centration method and compare induction of corneal higher order aberrations (HOAs) between the two methods.

METHODS

This study analyzed decentration values obtained from tangential topography difference maps of 100 eyes (100 patients) undergoing SMILE with the pupil center (n = 50) or tear film mark (n = 50) centration method. Total HOAs and component aberrations were measured preoperatively and 6 months postoperatively. Relationships between the magnitudes of decentration and induced corneal HOAs were assessed.

RESULTS

Both vertical and total decentered displacement were significantly different (P < .001) between the two centration groups. A significant relationship between the preoperative pupillary offset and decentration was noted in the pupil center group (P < .001), but not in the tear film mark group (P = .530). Significantly greater induction of total HOAs, coma, and vertical coma (all P < .001), as well as horizontal coma (P = .001) and spherical aberration (P = .023), were observed in the pupil center group. Association between the total decentered displacement and induced total HOAs (P < .001), as well as all other significantly increased phenomena, was also significant in the pupil center group. Differences in decentered displacement and induced corneal HOAs were significant for preoperative pupillary offset (angle kappa) greater than 200 µm, but not for angle kappa less than 200 µm.

CONCLUSIONS

SMILE with tear film mark centration can yield improved treatment centration and less induction of total HOAs, coma, and spherical aberrations. [J Refract Surg. 2020;36(4):239-246.].

Assessment of posture-induced cyclotorsion during cataract surgery using the Verion image-guided system

Background

The purpose of this prospective observational study is to analyse posture-induced cyclotorsion in eyes undergoing conventional phacoemulsification with toric intraocular lens (IOL) implantation and femtolaser-assisted cataract surgery (FLACS) using the Verion image-guided system.

Methods

Cyclotorsion was assessed in patients who underwent conventional phacoemulsification with toric IOL implantation and FLACS between June 2017 and November 2017 with registration of iris architecture, limbal and bulbar conjunctival blood vessels acquired preoperatively using the Verion Reference Unit (the patient in sitting position) and intraoperatively under the microscope using the digital marker of the Verion image-guided system with the patient in supine position.

Results

Forty-four eyes of 30 patients (21 men and 9 women) were included with the mean age of 56.5 ± 17.1 (range, 19-89; median, 62) years. The mean cyclotorsion induced by change in posture from sitting to supine position was 5.84 ± 3.25° (range, 1-17; median, 5). Overall, clockwise (CW) rotation (59.1%) was noted to be more common than counter clockwise (CCW) rotation (40.9%). Furthermore, CW rotation was more common in men than in women, and CCW rotation was significantly more common in women. Patients who underwent bilateral sequential cataract surgery show similar cyclorotation (CW or CCW) in both eyes more often than mixed rotation (85.7% vs 14.3%).

Conclusion

Significant cyclotorsion can occur in supine position during cataract surgery. Accurate assessment of the amount and direction of cyclotorsion aids in appropriate alignment of the toric IOL for optimal visual outcomes.

Wavefront-guided photorefractive keratectomy with and without iris registration: comparison of astigmatic correction

This study aimed to compare the visual outcomes after photorefractive keratectomy (PRK), with and without the iris registration (IR) technology. The retrospective cohort study was performed for wavefront-guided PRK using the Technolas 217z100 excimer laser system in patients with myopic astigmatism (cylinder error - 2 to - 4 diopter [D]). Eyes were divided into IR group (IRPRK) and non-IR group (non-IRPRK). Visual acuity (VA), cylindrical refraction, and the astigmatic vector components using the Alpins method were compared between the two groups preoperatively and 6 months postoperatively. Fifty IRPRK patients (66% female, mean age 30.56 ± 6.31 years) and 50 non-IRPRK (60% female, mean age 29.60 ± 5.63 years) were enrolled. The mean logMAR uncorrected VA improved from 0.89 ± 0.44 to 0.032 ± 0.05 in the IRPRK group (P < 0.001) and from 0.89 ± 0.46 to 0.042 ± 0.06 postoperatively while follow-up in the non-IRPRK group (P < 0.001). No statistically significant differences were observed between the two groups regarding mean uncorrected distance VA (P = 0.4), corrected distance VA (P = 0.5), spherical equivalent (P = 0.16), defocus equivalent (P = 0.18), and absolute cylinder (P = 0.94). More than 90% eyes were within ± 1.00 D of emmetropia in both groups. Moreover, Alpins vector analysis revealed that no significant differences were found in any astigmatic parameters between the two groups (P > 0.05). Wavefront-guided PRK independent of the IR status is effective, safe, and predictable in patients with myopic astigmatism. No statistical significance was observed supporting data for the better outcome of visual acuity and astigmatism correction using IR in comparison with a non-IR system.

Lower- and higher-order aberrations after photorefractive keratectomy with and without compensation of pupil centroid shift: fellow eye comparison

PURPOSE

To study the effect of pupil centroid shift (PCS) compensation on lower- and higher-order aberrations (HOAs) after photorefractive keratectomy (PRK).

SETTING

Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

DESIGN

Prospective intrasubject fellow eye study.

METHODS

One hundred twelve eyes of 56 patients with simple myopia or myopic astigmatism scheduled for PRK were enrolled. Preoperatively, the amount of PCS was measured in the horizontal and vertical directions. All eyes received wavefront-optimized treatment with static cyclotorsion compensation. PCS compensation was turned on for the right eye of each subject (PCS-on group), and turned off for the left eye (PCS-off group). Postoperatively, refraction and corneal HOAs were compared between the study groups at 6 months.

RESULTS

Mean preoperative myopia was -3.84 diopters (D) ± 2.41 (SD) vs -3.75 ± 2.27 D (P = .408), whereas mean preoperative cylinder was -1.18 D ± 1.15 (SD) vs -1.14 ± 1.16 D (P = .769) in the PCS-on and PCS-off groups, respectively. Mean absolute PCS values were 62.25 μm ± 41.82 (SD) vs 55.92 ± 37.47 μm (P = .45) in the horizontal direction and 65.04 ± 47.16 μm vs 58.40 ± 45.44 μm in the vertical direction (P = .29) in the PCS-on and PCS-off groups, respectively. The study groups were comparable in terms of postoperative refraction and root mean square of total corneal HOAs.

CONCLUSIONS

Compensation of PCS did not affect lower- and higher-order aberrations after wavefront-optimized PRK with static cyclotorsion compensation in myopic or myopic astigmatic eyes.

Cyclorotation during femtosecond laser-assisted cataract surgery measured using iris registration

PURPOSE

To assess ocular cyclorotation of eyes having femtosecond laser-assisted cataract surgery using iris registration.

SETTING

Eye Institute of West Florida, Largo, Florida, USA.

DESIGN

Retrospective cases series.

METHODS

Charts of patients who had femtosecond laser-assisted cataract surgery with preoperative and intraoperative iris registration in 1 or 2 eyes between November 2015 and March 2016 were reviewed. Cyclorotation was assessed via iris-registration acquired preoperatively using the Cassini topographer (patient in upright position) and intraoperatively using the iris registration option of the Lensar laser system (patient in supine position) acquired immediately before the laser treatment.

RESULTS

The study comprised 241 patients (337 eyes). The mean age of the 107 men and 134 women was 68.0 years ± 9.0 (SD) (range 37 to 90 years). The mean absolute value of cyclorotation was 5.81 ± 4.20 degrees (range 0 to 17 degrees), which was statistically significant when comparing the preoperative axis with the intraoperative axis deviation (P < .0001). Overall, incyclorotation (67.4%) was more common than excyclorotation (30.9%). In patients having bilateral femtosecond laser-assisted cataract surgery, bilateral incyclorotation (47.37%) was the most common occurrence.

CONCLUSIONS

During femtosecond laser-assisted cataract surgery, clinically significant cyclotorsion that might influence astigmatism correction outcomes can occur in patients having cataract extraction. Iris registration was useful in accounting for cyclorotation during this procedure when corneal or intraocular lens-based forms of astigmatic corrections will be used.

Surgically induced astigmatism in canines following sutured dorsonasal vs dorsotemporal clear corneal incisions

OBJECTIVES

To investigate use of the Pentacam® HR for evaluation of surgically induced corneal astigmatism (SIA) in canines undergoing bilateral phacoemulsification and determine differences between dorsonasal and dorsotemporal clear corneal incisions.

ANIMALS

Client-owned canines undergoing bilateral phacoemulsification.

PROCEDURES

Patients received anterior segment imaging pre-operatively, immediately post-operatively, and 2-4 months post-operatively (follow-up). Total corneal refractive power was used to determine SIA. Surgically induced astigmatism was compared between right and left eyes, representing dorsotemporal and dorsonasal incisions, respectively. Repeated measures analyses were used between time points and paired t test compared SIA between eyes.

RESULTS

Complete imaging series were obtained for seven patients. Follow-up imaging occurred at a median of 112 days (range 60-132 days) post-operatively. For repeated measures analyses, significant differences were found between pre- and immediate post-operative values (P < 0.01), and between immediate post-operative and follow-up values (P < 0.01). There was no significant difference between pre-operative and follow-up values. Surgically induced astigmatism was significantly different between right and left eyes, with values of 2.01 ± 1.24 D and 3.05 ± 1.58 D at 3 mm radius (P < 0.05), and 2.04 ± 1.18 D and 3.06 ± 1.27 D at 4 mm radius (P < 0.05) for dorsotemporal and dorsonasal incisions, respectively.

CONCLUSIONS

Preliminary investigation revealed improvement of corneal SIA 2-4 months post-operatively, but development of significantly more SIA in dorsonasal vs dorsotemporal incisions. This prompts consideration of patient or microscope rotation to create a more dorsotemporal incision when possible.

Recent advances in wavefront-guided LASIK

PURPOSE OF REVIEW

Laser vision correction remains an active area of research, and there have been many recent advances in the field. The purpose of this review is to provide an update on the recent advances for one of the most common methods of laser vision correction, wavefront-guided laser in-situ keratomileusis (LASIK).

RECENT FINDINGS

Recent technological advancements in wavefront aberrometry are largely responsible for the improved visual outcomes that have been recently reported. In addition, improvements in femtosecond and excimer laser technology, used in flap creation and corneal ablation, have been shown to provide superior results when compared to microkeratomes and earlier lasers. Wavefront-guided LASIK appears to have advantages over some other keratorefractive modalities in terms of visual acuity, predictability, astigmatism correction, and subjective visual symptoms. Nonetheless, there may be some limitations in highly aberrated corneas, and also in biomechanical stability relative to other available platforms.

SUMMARY

Improvements in wavefront aberrometry, and also femtosecond and excimer lasers, have continued to improve our ability to correct refractive errors. Wavefront-guided LASIK remains a well tolerated and effective keratorefractive procedure, with a trend toward superiority. Nonetheless, further studies comparing this modality to others are needed to define the role each can serve.

Factors Influencing Cyclotorsion During Photorefractive Keratectomy

PURPOSE

To determine predictive factors for intra-operative cyclotorsion in photorefractive keratectomy (PRK).

METHODS

A retrospective statistical analysis of medical records pertaining to 3,996 eyes undergoing PRK was conducted. Outcome measures of this study were the likely existence of statistically significant relations between diverse and potentially influential factors and the occurrence of intraoperative cyclotorsion.

RESULTS

A total of 96% of examined medical records indicated some degree of cyclotorsion with the absolute mean intraoperative value of 1.38° ± 1.67° (range: 0° to 13.6°). Absolute mean cyclotorsion showed no significant correlation with age (r = 0.14, P = .37). Female patients had significantly higher degrees of cyclotorsion versus males (P < .001). Right and left eyes showed no significant difference in absolute mean torsion (P = .05). Higher diopters of refractive errors, hyperopia, more than 2.00 diopters of cylinder, high pulse numbers (r = 0.26), and use of the advanced personalized treatment ablation algorithm were all significantly related to higher degrees of torsion (P < .0001). Ablation depth (r = 0.13) and surgeon appeared to be dependent factors.

CONCLUSIONS

Incidence of intraoperative cyclotorsion is high in eyes undergoing PRK and most of them will experience some degree of torsion. Several diverse factors (sex, refractive error diopters, hyperopia, high cylinder, pulse numbers, and ablation algorithm) were significant predictors for higher degrees of the observed torsion. [J Refract Surg. 2018;34(2):106-112.].

Effect of Iris registration on visual outcome in wavefront-guided LASEK for myopic astigmatism

PURPOSE

This study aimed to investigate the effect of iris registration (IR) on visual outcomes in wavefront-guided LASEK for myopic astigmatism.

METHODS

The retrospective chart review was performed for wavefront-guided LASEK using VISX Star S4 in patients with myopic astigmatism (cylinder ≥ 1.00 diopter[D]). Eyes were divided into IR group (LASEK with IR at the time of surgery) and Non-IR group (LASEK without IR system + failed-IR engagement during LASEK). Visual acuity (VA), astigmatism, higher-order aberration (HOA), and contrast sensitivity were assessed preoperatively and 3 months postoperatively. The IR and Non-IR groups were subcategorized depending on the spherical equivalent (lower myopia ≤-5.00 D vs. higher myopia >-5.00 D) for the comparison of HOA changes.

RESULTS

Postoperative uncorrected VAs showed no differences between IR (n = 30) and Non-IR (n = 46). In astigmatic vector analyses, no differences were noted in the mean magnitude of error and the mean angle of error between two groups. There were no differences in postoperative total HOA, spherical aberration (SA), coma, and trefoil between the groups, either. The total HOA and SA increased in both groups, while coma increased only in Non-IR. In higher myopia, ΔRMS of coma was smaller in IR. Preoperative and postoperative total HOA were linearly correlated in Non-IR, but not for IR. Contrast sensitivity of 12 cycles per degree improved in both groups.

CONCLUSION

IR had similar outcomes to conventional trackers in wavefront-guided LASEK, with less tendency of inducing coma, especially in higher myopia.

Influence of blurred vision, accommodation, and target laser settings on eye movements during LASIK

PURPOSE

To analyze the influence of blurred vision, accommodation, and target laser settings on eye movements during laser in situ keratomileusis (LASIK).

SETTING

Department of Ophthalmology, Goethe University, Frankfurt, Germany.

DESIGN

Prospective randomized study.

METHODS

Participants had simulated LASIK treatment. They were instructed to focus on the fixation light; the treatment laser was blocked, and all other settings were applied according to standard LASIK treatments. To simulate blurred vision a 0.0 diopter (D) soft contact lens received a 5.0 D myopia laser treatment and was then applied to the participant's eye. To diminish accommodation, a second lens that had a refraction of the patient's spherical equivalent, plus 3.0 D to compensate for accommodation, was used. There were 4 treatment modalities as follows: (1) blurred lens with target laser on, (2) blurred lens with target laser turned off, (3) +3.0 D lens with target laser on, and (4) +3.0 D lens with target laser turned off. Lateral and torsional eye movements were recorded. Fourier analysis was used to obtain temporal power spectra from dynamic eye movements. The Fn criterion was set as the frequency below which n% of eye movements in the cohort occurred (n = 95%, 80%, and 50%).

RESULTS

The study comprised 11 eyes of 11 participants. There was 1 significant difference between the eye movements based on measurement modalities. In 1 variable in the y-axis, there was movement that showed a significant difference in the F80 criterion.

CONCLUSION

Surgical circumstances such as blurred vision, accommodation, and target light had little influence on eye movements during LASIK.

FINANCIAL DISCLOSURE

Proprietary or commercial disclosures are listed after the references.

Laser in Situ Keratomileusis for High Hyperopia with Corneal Vertex Centration and Asymmetric Offset

Purpose

To investigate refractive outcomes and induction of corneal higher order aberrations (HOA) in eyes that underwent laser-assisted in situ keratomileusis (LASIK) for high hyperopia correction using an aberration neutral profile with corneal vertex centration and asymmetric offset.

Methods

A total of 24 consecutive patients (38 eyes) who underwent LASIK by one surgeon using AMARIS 750S excimer laser and a Carriazo-Pendular microkeratome for flap creation were retrospectively analyzed. Eyes targeted for plano and with correction in the maximum hyperopic meridian strictly higher than +4D were included in the retrospective analysis. Patients were reviewed at 1, 3, and 6 months postoperatively. Postoperative monocular corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA), manifest refraction, and corneal wavefront aberrations were compared with respective preoperative metrics.

Results

Mean preoperative spherical equivalent and refractive astigmatism was +4.07 ± 0.90 D and 1.37 ± 1.26 D, respectively, reducing to +0.28 ± 0.58D (p<0.0001) and 0.49 ± 0.47 D (p = 0.0001) at the last postoperative visit. Six months postoperatively, 78% of eyes achieved a UDVA of 20/25 or better. No eye lost more than 2 Snellen lines of CDVA at any follow-up. There was a statistically significant induction of vertical trefoil (+0.104 ± 0.299 µm, p<0.05), vertical coma (-0.181 ± 0.463 µm, p<0.01), horizontal coma (+0.198 ± 0.663 µm, p<0.05), spherical aberration (-0.324 ± 0.281 µm, p<0.0001), secondary vertical trefoil (+0.018 ± 0.044 µm, p<0.01), and secondary horizontal coma (+0.026 ± 0.083 µm, p<0.05)

Conclusions

Laser-assisted in situ keratomileusis for high hyperopia using corneal vertex centration with asymmetric offset results in significant improvement in refraction and visual acuity although affected by significant induction of some higher order aberrations.

Clinical utility and assessment of cyclodeviation

PURPOSE OF REVIEW

This article reviews and updates basic concepts, diagnosis and treatment of cyclotorsion.

RECENT FINDINGS

Cyclodeviation in congenital superior oblique palsy (SOP) seems to correlate with the extent of superior oblique muscle hypoplasia. Genetic polymorphisms such as PHOX2B polymorphism, considered to be risk factors for congenital fibrosis of the extraocular muscles, may play a role in SOP and consequently in cyclotorsion. Two components of the ocular tilt reaction, ocular torsion and tilt of subjective visual vertical, seem to share similar sites of impairment in the brainstem. Harada-Ito surgery continues to be the procedure of choice in patients with isolated cyclodeviation, evidencing better outcome if less than 10° of preoperative excyclotorsion and preoperative fusion exist. Ocular torsion is not infrequent in patients with intermittent exotropia, especially in the most exo-deviated eye, emphasizing a possible role in pathogenesis. A new device for the assessment of dynamic torsion during ocular counter roll response using after-image has been described. Similarly, a new method to measure objective ocular torsion using retinal arcade tilt as a reference has been proposed. Finally, torsional data transformation such as the sum of angles of excyclodeviation, rather than using the angle of excyclodeviation of the paretic eye, is becoming increasingly popular among studies on torsion.

SUMMARY

Exciting developments on ocular torsion have been described recently, and new ways to access and interpret ocular torsion have been devised as well.

Eye movement testing in clinical examination

The clinical vision examination routinely includes an evaluation of ocular motor function. In a number of diverse situations, thorough objective recording of eye movements is warranted, using any of a variety of eye-tracking technologies that are available currently to clinicians. Here we review the clinical uses of eye tracking, with both an historical and contemporary view. We also consider several new imaging technologies that are becoming available in clinics and include inbuilt eye-tracking capability. These highly sensitive eye trackers should be useful for evaluating a variety of subtle, but important, oculomotor signs and disorders.